Process of preparing zinc formaldehyde sulfoxylate.



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Lett efs l'ajtent. Patented 061i). 5, 1939.

, Applicationiiledflarchiw,1908. SeriaINo. 423,429.

To all @vhom it may concern: I Be it known that I, FERDINAND RADEP. MACHER, manufacturer, citizen of Austria,

subject'of the Emperor of-Austria-Hungary,

residing at Prague-Karolinenthal, in the Kingdom of Bohemia and Empireof Austria-Hungary, have invented certain new and useful Improvements in Processes of .Preparing a Slightly-Soluble Zinc Formaldehyde Sulfoxylate,.of which the following is a full, clear, andexact description; I

By the known process of production of formaldehyde sulfoxylates from formaldehyde-.alkali-bisulfite, .the alkaline salt of formaldehydesulfoxylicacid is obtained mixed with other salts which accompany it int-he solution and render it impure. The

' manufacture in pure formof formaldehyde s'ulfoxyla tefromthese solutions is no simple for this purpose.

matter, as is evident from the very fact that there exist descriptions of special processes It has beenfound however that formaldehyde-alkali-bisulfite can, in a singleoperation, in the very easiest way, be

convertedinto the almost insoluble zinc salt of formaldehyde sulfoxylic acid-the said zinc salt being free from every foreigirsalt after some washing if powder of zinc is al-' stirring.

.lowedito acton formaldehydea1kali-bisulfitef mthe presence of zinc salts, such as acetate of:z1nc, chlor1d'of zinc, sulfate of Z1110 etc.

The'presenee of the zinc salt renders reduction so easy that in order to' obtain a high rate of. yield neither a considerable excess of powder of zinc is required nor does the concentration of the liquid play any part. If concentrated solutions of bisulfite, the zinc Salt and formaldehyde be employed, the. mixture soon thickens, and it must be stirred up until 'a thick dough. results, which .is allowed to co tinue on theowater bath until completion of the re-action without further In this way there is obtained a dry mass which, after coolin m find application in that form, or e se, a or lixivmtion with water, is converted by means of alkali and ields formaldehyde alkali sulfox late of a lute purity. When working wit dilutesolutions it is advisable to stir contixn oxylate is filtered salts by washin ,Example I: %o formaldehyde-bisulfite produced from 250 parts by weight of sodium bisulfite of 38 degrees Baum and parts byweight of 40 per cent. formaldehyde-there are added parts by weight of chlorid of zinc lye of 52' degrees Baiun and 120 parts of powder of zinc; this is heated to near boiling point and then allowed'to stand in the water bath. According as the thickening mass requires, it is stirred from time to time so that it always forms a uniform dough. \Vithin about half an hourat most the mass forms a stiff paste,

time in the Water-bath without further stirring.

Example II: Formaldehyde-sodium-bisulfite produced from 250 parts by weight of sodium-bisulfite of 38 degrees Baum and 75 arts by weightof 40 per cent. formaldeand there are added zinc acetate and 120 parts of Z1110 powder; The whole is heated, thoroughly-stirring the while, for 2 or three hours until it boils.

inaldehyde-zinc-sulfoxylate separates out; it is filtered and washed.

What I claim is: I 1. The process of preparing substantially insoluble zinc formaldehyde sulfoxylate which consistsin reacting on a solution of powder in presence of asoluble zinc salt.

2. I-he process of preparin substantially insoluble zinc formaldlshyde sulfoxylate which consists in heating nearly to the'boiling point a solution ofan-alkali formaldehyde-bisulfite together with zinc powder and a soluble zinc salt.

In .witness whereof, I subscribe my signs ture, in presence of two witnesses.

FERDINAND RAUEMAC-lilfill.

Wimesses:

Armies Senweia M. L. Erin's-ms.

ually; the resulting formaldehyde zinc-sulfand cleaned of foreign which is allowed to stand for some further an alkali formaldehyde-bisulfite with zinc hy e is diluted with' 1000 parts of water parts by Weight of y During the process the low-solubility for 

